Interpretive Summary: The sorghum [Sorghum bicolor (L.) Moench] has emerged as a promising bioenergy plant. Many molecular and genetic tools, such as genetic maps and genome sequence, are available to improve the bioenergy traits in sorghum. However, an important genetic resource, a mutant population, is still missing in the sorghum, compared with other model species. The lack of a mutant population is a major limitation for many avenues of research, especially those focusing on functional genomics and bioenergy research. Here we report the generation of a sorghum mutant population derived from the inbred line BTx623 by treatment with the chemical agent ethyl methanesulfonate (EMS). The mutant population consists of 1,600 pedigreed M3 families; each of them was derived from an independent M1 seed. Many lines displayed traits such as brown midrib (bmr), erect leaves (erl), multiple tillers (mtl), and late flowering (lfl), characteristics useful for bioenergy research. Results from phenotyping and genotyping studies indicate that this mutant population will be a valuable and useful genetic resource for both sorghum functional genomics and bioenergy research. The availability of such mutant population will undoubtedly speed up the bioenergy research in sorghum.

Technical Abstract:
The sorghum [Sorghum bicolor (L.) Moench] inbred line BTx623 has served as a parent for development of several mapping populations, also providing a source for the generation of DNA libraries for physical mapping, and as the inbred line selected for sorghum genome sequencing. Since genetic mapping, physical mapping and genome sequencing are all based on the same inbred line, these genetic resources have made the genome study of sorghum very efficient. However, in comparison with other model species, there is one important genetic resource still missing in the sorghum research community, a mutant population. The lack of a mutant population is a major limitation for many avenues of research, especially those focusing on functional genomics and bioenergy research. Here we report the generation of a sorghum mutant population derived from the inbred line BTx623 by treatment with the chemical agent ethyl methanesulfonate (EMS). The mutant population consists of 1,600 pedigreed M3 families; each of them was derived from an independent M1 seed. Many lines displayed traits such as brown midrib (bmr), erect leaves (erl), multiple tillers (mtl), and late flowering (lfl), characteristics useful for bioenergy research. Results from our phenotyping and genotyping studies indicate that this mutant population will be a valuable and useful genetic resource for both sorghum functional genomics and bioenergy research. The utility of the mutant population, some mutant phenotypes and their potential utilization for bioenergy research are discussed.